Usage Of Fly Ash Research Articles

Development of quaternary blended high performance concrete made with high reactivity metakaolin

In the last three decades, supplementary cementitious materials such as fly ash, silica fume and ground granulated blast furnace slag have been judiciously utilized as cement replacement materials as these can significantly enhance the strength and durability characteristics of concrete in comparison with ordinary Portland cement (OPC) alone. Hence, high-performance concretes can be produced at lower water/powder ratios by incorporating these supplementary materials. One of the main objectives of the present research work was to investigate synergistic action of binary, ternary and quaternary blended high strength grade (M80) concretes on its compressive strength. For blended high strength grade (M80) concrete mixes the optimum combinations are: Binary blend (95%OPC +5% FA, 95%OPC +5% MS and 95%OPC +5%MK), ternary blend (65%OPC+20%FA+15%MS) and quaternary blend (50%OPC+28%FA+11%MS+11%MK). Use of metakaolin in fly ash based blended concretes enhances compressive strength significantly and found to be cost effective in terms of less cement usage, increased usage of fly ash and also plays a major role in early strength development of fly ash based blended concrete.

Mercury release from fly ashes and hydrated fly ash cement pastes

The large-scale usage of fly ash in cement and concrete introduces mercury (Hg) into concrete structures and a risk of secondary emission of Hg from the structures during long-term service was evaluated. Three fly ashes were collected from coal-fired power plants and three blend cements were prepared by mixing Ordinary Portland cement (OPC) with the same amount of fly ash. The releasing behaviors of Hg0 from the fly ash and the powdered hydrated cement pastes (HCP) were measured by a self-developed Hg measurement system, where an air-blowing part and Hg collection part were involved. The Hg release of fly ashes at room temperature varied from 25.84 to 39.69 ng/g fly ash during 90-days period of air-blowing experiment. In contrast, the Hg release of the HCPs were in a range of 8.51–18.48 ng/g HCP. It is found that the Hg release ratios of HCPs were almost the same as those of the pure fly ashes, suggesting that the hydration products of the HCP have little immobilization effect on Hg0. Increasing temperature and moisture content markedly promote the Hg release.

Effect of Heat Treatment on Mechanical Behaviour of Fly ash Reinforced Al-Si Composite - A Review

In recent years the use of metal matrix composite material increased very rapidly due to their high weight to strength ratio, low density, low thermal expansion coefficient, low maintenance and high temperature resistance. The composites which are reinforced with fly ash particulates attracting considerable interest due to their inherent good mechanical properties and low cost followed by Heat Treatment to achieve desired physical and mechanical properties through modification of their crystalline structure of the materials. This paper provides an extensive literature review on the overall performance of varying the size and wt. percentage of fly ash in fly ash reinforced composites with aluminium alloy. Literatures in each category are reviewed according to the keywords mentioned. The literature review framework in this paper provides a clear overview of the usage of fly ash as a reinforcing agent in different matrices along with its distinctive performances.

Laboratory investigation of hydraulic characteristics of fly ash as a fill material from the aspects of pollutant transport.

Depending on the usage of fly ash, it is necessary to determine its environmental parameters, such as the potential for pollutant transport/leaching after its built-in. This study presents a methodology for determination of transport parameters (filtration coefficient, effective porosity, longitudinal dispersivity, and the mean residence time) from experimental data collected from column experiments with a conservative tracer on different mixtures of fly ash with stabilizers (4.8% lime and 5% cement). The transport parameters are determined using (1) numerical model results and (2) an adapted analytical solution results against measured outflow tracer concentrations. The study shows that the addition of stabilizers decreases the filtration coefficient by an order of magnitude and the effective porosity by half. The longitudinal dispersivity is not influenced by the addition of lime to the mixture, and is increased by 40% by the addition of cement. The pollutant contact time with fly ash increases by six or nine times with the addition of lime and cement, respectively. The adaptation of the analytical solution agrees well with both the numerical solution and the experimental results, and it is anticipated to be of high value for determination of transport parameters for practitioners not familiar with numerical methods.

Usage of Fly Ash and Waste Slime Boron for Soil Stabilization

Waste materials are hazardous and serious problem for environment. Because, they occur soil pollution, ground water pollution and also visual pollution. Especially, industrial wastes are composed in large quantities. Many scientists have made research to solve these problems. According to their results, they have suggested that usage of waste materials in many areas as a material or additive material. One of the areas is soil stabilization. Soil properties are improved with this additive wastes. In this study, laboratory tests were conducted on granular soil specimens amended with fly ash and slime waste boron. The specimens were prepared with granular soil and fly ash-waste boron at different ratios. They were compacted standard Proctor compaction energy and, than were cured 1, 7 and 28 days. After cure unconfined compressive tests were conducted to investigate the effect of fly ash-waste boron on granular soil strength. Addition of fly ash-waste boron increased soil strength. As a result, fly ash-waste boron can be used with granular soil for increasing strength. This is economical solution.

Effect of Heat Treatment on Mechanical Properties of Aluminium alloy-Fly ash Metal Matrix Composite

In recent years the use of metal matrix composite material increased very rapidly due to their high weight to strength ratio, low density, low thermal expansion coefficient, low maintenance and high temperature resistance. The composites which are reinforced with fly ash particulates attracting considerable interest due to their inherent good mechanical properties and low cost followed by Heat Treatment to achieve desired physical and mechanical properties through modification of their crystalline structure of the materials. This paper provides an extensive literature review on the overall performance of varying the size and wt. percentage of fly ash in fly ash reinforced composites with aluminium alloy. Literatures in each category are reviewed according to the keywords mentioned. The literature review framework in this paper provides a clear overview of the usage of fly ash as a reinforcing agent in different matrices along with its distinctive performances.

Critical factors for the successful usage of fly ash in roads & bridges and embankments: Analyzing indian perspective

Fly ash has been recognized as hazardous material causing air, soil and water pollution. Fly ash a ‘waste by-product’ of electricity generation from power plants (coal-based thermal) has an estimated annual production of approximately two hundred million tons. In-spite of many problems associated (like land requirement for disposal, toxicity to groundwater, handling issues etc.); we have started treating fly ash as a resource material. Present research addresses usage of fly ash in roads & bridges and embankments. In the present study, an attempt has been made to recognize and analyze comprehensively key elements and sub-elements of program implementation of fly ash usage and further to segregate Critical factors (CFs) of usage of fly ash in roads & bridges and embankments. Eight relevant CFs have been recognized for usage of fly ash in roads & bridges; and ten CFs for the usage of fly ash in embankments. Thereafter, Interpretive Structural Modeling (ISM) approach has been applied on these CFs and two models of driver CFs, linkage CFs and driven CFs have been obtained. Appropriate discussions along-with MICMAC analysis in the light of important elements and sub-elements have helped to present managerial implications useful for stakeholders.

Properties of mortars with fly ash as fine aggregate

Coal power plants produce million tons waste fly ash worldwide that cause environmental problem and threaten people health. Moreover, its depoting costs are high and need extensively large depot areas. Recycling is a strategy to consume waste content left from several industries. Although fly ash has been used in cement and concrete technology. In concrete technology it has been used as supplementary cementitious material or replacement material with a portion of cement until now. But, it has not been considered as fine aggregate. In this study, the effect of fly ash as fine aggregate in mortars is investigated. Flow ability, unit weight, ultrasound pulse velocity, compressive and flexural strengths, modulus of elasticity, stress–strain behavior and free drying and restrained shrinkage tests were conducted on mortars produced. It was observed that the usage of fly ash as fine aggregate presents a new approach to consume high amount of fly ash without causing significant changes on properties of mortars when it was used at the ratio of 60–70%.

ゼオライト高含有硬化体に及ぼすアルカリ濃度の影響

The discharge amount of coal ash was around 10 million tons every year from pulverized coal-fired power plants in Japan, so some efficient usage of fly ash is needed. Alkali activated aluminosilicate material, i.e. fly ash, attracts attention as a new usage of fly ash. Authors reported that the hardened material made of fly ash and sodium hydroxide with curing under hydrothermal condition at 180℃ obtained high strength and high cation exchange ability against cesium. This paper discusses the influence of mixing ratio among fly ash, sodium hydroxide and water on physicochemical properties of hardened material. We mainly focused on optimal mixing ratio between fly ash and sodium hydroxide to obtain high cation exchange capacity, CEC, with high adsorption performance against cesium ion. Through the parametric experiments, it was found that there are optimal mixing ratio between fly ash and sodium hydroxide to obtain high strength with enough amount of composed zeolite, and characteristic tendency between CEC and adsorption performance against cesium. With the increase in dosage of sodium hydroxide, CEC increased with reduction of adsorption performance against cesium. When NaOH/FA and water/FA was 8.2mass% and 33.8mass% respectively (molarity of NaOH was 5.9mol/L), hardened zeolite had high strength (σc=52.1N/mm2, σb=10.3N/mm2), cation exchange capacity (CEC, 152cmol/kg) and adsorption ability of cecium (Kd=35.4L/g).

비산재를 활용한 해수 알칼리도 증대 및 흡수액의 알칼리도가 탈황 효율에 미치는 영향

비산재를 활용한 해수 알칼리도 증대 및 흡수액의 알칼리도가 탈황 효율에 미치는 영향

Effect of polypropylene fibre on flexural properties of concrete composites containing fly ash and silica fume

The application of fly ash and silica fume in concrete composites by blending synchronously can improve the mechanical properties of concrete composites. However, the concrete composite becomes much brittle with the usage of fly ash and silica fume. Polypropylene fibre is often used to improve the ductility of concrete composites. This article discusses the effect of polypropylene fibre on the flexural properties of concrete composites containing fly ash and silica fume. Results reveal that the addition of polypropylene fibre can increase the flexural strength and decrease the flexural modulus of elasticity of the concrete composite containing fly ash and silica fume evidently. Furthermore, it is indicated that an increase in the fibre volume fraction leads to an increase in the flexural strength and a decrease in the flexural modulus of elasticity when the fibre volume fraction is not beyond 0.12 per cent. Polypropylene fibre seems to play an important role to improve the ductility of concrete composites containing fly ash and silica fume.

Static Model Test on Fly Ash Embankment of Expressway

The usage of fly ash in constructing expressway is more and more extensive and the technology of constructing is becoming to more and more mature. But the stability and failure mode of the embankment is lack of researches. In order to study the stability and failure mode of the embankment, the plan for the study of the static model test of light fly ash embankment was designed, in which the model material was selected based on the similarity principle of the model test. The mechanical characteristic under static load is simulated. The internal force, the relationship between the stress and load, the displacement and load of different depth of the embankment were obtained through the test. The deformation and mechanical characteristic is studied and the influence of concrete pavement is also considered. The experimental results show that the high filling subgrade has an excellent stability and high bearing capacity and the influence of the concrete pavement is relatively large.

フライアッシュセメントと界面活性剤の混合材料を用いた管更生用中込材の開発

In recent years, many trenchless rehabilitations of pipeline that are considered of residents' living environment and mitigated the influence on traffic have been developed. Although the grouting material is required to make the established pipe and the lining material unify, it has high mobility etc. The grouting material using the material that was mixed the surface-active agent with the flyash was developed. Usage of flyash instead of cement leads to improving mobility, reducing construction cost and so on. In this paper, in order to examine the effect on ambient surroundings of the mixture material developed as grouting material, a fundamental investigation is performed and various these results are discussed.

An experimental study on strength development of concrete containing fly ash and optimum usage of fly ash in concrete

This paper presents a laboratory study on the strength development of concrete containing fly ash and optimum use of fly ash in concrete. Fly ash was added according to the partial replacement method in mixtures. A total of 28 mixtures with different mix designs were prepared. 4 of them were prepared as control mixtures with 250, 300, 350, and 400 kg/m 3 cement content in order to calculate the Bolomey and Feret coefficients ( K B, K F). Four groups of mixtures were prepared, each group containing six mix designs and using the cement content of one of the control mixture as the base for the mix design. In each group 20% of the cement content of the control mixture was removed, resulting in starting mixtures with 200, 240, 280, and 320 kg/m 3 cement content. Fly ash in the amount of approximately 15%, 25%, 33%, 42%, 50%, and 58% of the rest of the cement content was added as partial cement replacement. All specimens were moist cured for 28 and 180 days before compressive strength testing. The efficiency and the maximum content of fly ash that gives the maximum compressive strength were obtained by using Bolomey and Feret strength equations. Hence, the maximum amount of usable fly ash amount with the optimum efficiency was determined. This study showed that strength increases with increasing amount of fly ash up to an optimum value, beyond which strength starts to decrease with further addition of fly ash. The optimum value of fly ash for the four test groups is about 40% of cement. Fly ash/cement ratio is an important factor determining the efficiency of fly ash.

Proportioning of Fly Ash Cement Concrete Mixes

Abstract The accumulation of fly ash throughout the world is several million tons per day. The main problem with the usage of fly ash is the slow rate of strength gain, primarily due to slow pozzolanic reactions. Existing methods of proportioning fly ash concrete are lacking. These methods are involved and do not directly take into account the properties of the constituent materials. The Generalized Approach for Mix Proportioning developed at the Indian Institute of Science, Bangalore, is the basis for the development of the proposed method, which takes into account the characteristics of cement, fly ash, and aggregates. Based on the basic trial mix data obtained by using the American Concrete Institute (ACI 211.1-81) method, the proportions of fly-ash concrete mixes were arrived at using the Generalized Approach for Mix Proportioning. The method proposed was applied to and found applicable for fly-ash concretes using fly ashes from two different sources.